Density Measurements Using Coherence Imaging Spectroscopy Based On Stark Broadening

A coherence imaging camera has been set up at Pilot-PSI. The system is to be used for imaging the plasma density through the Stark effect broadening of the H(gamma) line. Local density values are then obtained by the Abel inversion of the measured interferometric fringe contrast. This report will present the instrument setup and proof-of-principle demonstration. The inverted spatial electron density profiles obtained near the cascaded arc source of Pilot-PSI in discharges with axial magnetic field of B=0.4 T are compared with an independent measurement of electron density by Thomson scattering and good agreement is found. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3490023]